6 Answers
6

If it ain't broke, don't fix it. Do you have a support contract that VMware won't honour or something, are you constantly finding show-stopping bugs in VMware Server that prevents you from working on it until a patch is issued?

VMware vSphere Hypervisor (aka ESXi) is a free, bare-metal hypervisor. It's easy to migrate your VMs from VMware Server to vSphere using VMware Converter. In addition to running your existing VMs, vSphere can be upgraded later to add features such as redundancy and live migration.

If you don't need to run your VMs headless, you could use VMware Player (free) or VMware Workstation ($200), both of which can also easily import your existing VMs. VMware Workstation 8 also includes a new sharing feature.

Depending on what kind of testing you do, you might be interested in the clone and snapshot features in vSphere and Workstation. These features make it easy to configure and rollback test machines.

One of the reasons we've retired VMware Server at my office is that the management plugin is no longer updated, and won't run in newer versions of Firefox.

I use Proxmox VE myself for about 3 years now, very happy about it. It's basically KVM + OpenVZ + Debian + their own custom webui. It's very user-frinedly, you manage it form the web much like the old VMware server.

I didn't want to go with VMware vSphere or Citrix XenServer as they both run on hypervisor kernels, and may have rather picky hardware requirements.

It comes with KVM guest VM images and OpenVZ-enabled guest kernels for many major Linux distro, available for download within the VM guest setup screen.

There were any mature KVM distro when I selected Proxmox VE, but apperently there's another one based on RHEL/CEntos called OpenNode